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46 lines
1.3 KiB
Markdown
46 lines
1.3 KiB
Markdown
---
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title: "Quick Python: Abstract Classes"
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date: 2020-01-26T18:40:03-05:00
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draft: false
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tags: [ "python" ]
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---
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You can create an abstract class in Python by inheriting Abstract Base Class (`ABC`) and declaring relevant methods abstract.
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First import the following from the standard library,
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```python
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from abc import ABC, abstractmethod
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```
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Then create an abstract class, making sure to add the decorator `@abstractmethod` to the constructor. This prevents the user from instantiating the class.
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```python
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class Animal(ABC):
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@abstractmethod
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def __init__(self, name):
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self.name = name
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@abstractmethod
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def is_bipedal(self):
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pass
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def speak(self):
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return "Hello my name is " + self.name + " and I am a " + type(self).__name__
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```
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In the example above:
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- A constructor is made, however, the class Animal cannot be instantiated. Do note that child classes can call the constructor.
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- `is_bipedal` is an abstract method that needs to be defined in child classes. `pass` indicates that it is not implemented.
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- `speak` is a normal method that will be inherited by child classes.
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Now let's look at a class that inherits `Animal`.
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```python
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class Dog(Animal):
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def __init__(self, name, owner):
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super().__init__(name) # Calls Animal constructor
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self.owner = owner
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def is_bipedal(self):
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return False
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```
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